Voltage regulators are widely used for providing an approximately constant output voltage. A voltage regulator often comprises an output transistor which is controlled by a voltage depending on the output voltage of the voltage regulator.
Document G. A. Rincon-Mora, P. E. Allen, “A Low-Voltage, Low Quiescent Current, Low Drop-Out Regulator”, IEEE Journal of Solid-State Circuits, volume 33, no. 1, January 1998, pp. 36-44, shows a voltage regulator comprising an output transistor, a voltage divider and an amplifier, wherein the amplifier controls the output transistor depending on the output voltage and a reference voltage.